1. Field of the Invention
The present invention concerns switch knobs for electronic devices and in particular a switch knob of the type having a mobile part adapted to switch from one contact to another on rotation and a second part fixed to a support of the device on which the switch knob is mounted by assembly means and clamping means.
2. Description of the Prior Art
Switch knobs are usually fixed to the support of the device by means of a location whose shape mates with the periphery of the fixed part of the switch knob. Unfortunately, even the slightest play during assembly and the play created between the fixed part of the knob and its housing following repeated manipulation of the switch knob lead to an angular offset of the mobile part relative to its reference position which can lead to erroneous reading of indications associated with the switch knob.
This kind of problem has been solved in the prior art by fixing the switch knob to the printed circuit or by mounting the knob on a jig which positions it during clamping. Unfortunately, this type of mounting does not provide the seal required if the electronic device on which the knob is mounted is to be used out of doors, as in the case of a mobile telephone, for example.
Consequently, an object of the invention is to provide a switch knob which is fixed to its support in a sealed manner and which prevents even minimal play leading to erroneous reading of knob indications.